Studies with bacterial mutants producing elevated levels of the histidine transport components will be continued, especially those involving selection of a hisP-carrying plasmid and those on regulatory mutants. Analysis of these mutants will involve scanning of total bacterial protein by two-dimensional gel electrophoresis and transport studies in membrane vesicles. We will attempt at reconstituting the vesicle transport system by adding the binding protein back to vesicles. The possibility of an interaction between the J and the P proteins will be explored extensively. The search for a precursor of the J protein, in connection with the existence of multiple mutant forms of the J protein, will be investigated by protein chemistry studies of the mutant J proteins and active search for a precursor by antibody precipitation.